To:
Robert Elz <kre@munnari.OZ.AU>
Cc:
ngtrans@sunroof.eng.sun.com, namedroppers@ops.ietf.org, ipng@sunroof.eng.sun.com, dnsop@cafax.se
From:
Daniel Senie <dts@senie.com>
Date:
Wed, 08 Aug 2001 12:12:15 -0400
In-Reply-To:
<4979.997285484@brandenburg.cs.mu.OZ.AU>
Sender:
owner-dnsop@cafax.se
Subject:
Re: (ngtrans) Joint DNSEXT & NGTRANS summary
At 11:44 AM 8/8/01, Robert Elz wrote: > Date: Wed, 08 Aug 2001 11:13:52 -0400 > From: Daniel Senie <dts@senie.com> > Message-ID: <5.1.0.14.2.20010808111308.03f697d0@mail.amaranth.net> > > | Not to mention melting the 'net under ever increasing DNS load, since > we'd > | no longer be able to cache anything. > >Huh??? > >No-one ever said anything about changing the definition or use of the >TTL field in DNS replies. If you get a TTL that says an address is >valid for a day, then you can keep using it for a day without checking >again. Or you can check again every 5 minutes if you want to, but >the answers will just keep coming back from your local cache, each with >a TTL 5 minutes shorter than the previous time... Reread what Keith wrote. If applications are going to use DNS to check for changes in addressing, how is caching going to help? You're suggesting the local caches just answer the every-5-minute lookups, but that's useless if the DNS lookups are used as a part of multihoming. I interpreted the periodic lookup as being a way for applications to find out that a remote machine has migrated to a new address. If local caches mask that migration, how's that help? Multihoming has to involve resiliancy. If the addresses are cached for a day, saying "oh, your application will start working again tomorrow" is unlikely to cut it. So, I guess the question back to the original point was, what information is going to be IN those lookups that happen every 5 minutes? If that information needs to change on a minute by minute basis (or a 5 minute by 5 minute basis) then caching is not going to help. So, the question is, to use this effectively, do zones have to be set up with their TTL set to 60 seconds? ----------------------------------------------------------------- Daniel Senie dts@senie.com Amaranth Networks Inc. http://www.amaranth.com